Publication Date:
2008-03-08
Description:
Time has always had a special status in physics because of its fundamental role in specifying the regularities of nature and because of the extraordinary precision with which it can be measured. This precision enables tests of fundamental physics and cosmology, as well as practical applications such as satellite navigation. Recently, a regime of operation for atomic clocks based on optical transitions has become possible, promising even higher performance. We report the frequency ratio of two optical atomic clocks with a fractional uncertainty of 5.2 x 10(-17). The ratio of aluminum and mercury single-ion optical clock frequencies nuAl+/nuHg+ is 1.052871833148990438(55), where the uncertainty comprises a statistical measurement uncertainty of 4.3 x 10(-17), and systematic uncertainties of 1.9 x 10(-17) and 2.3 x 10(-17) in the mercury and aluminum frequency standards, respectively. Repeated measurements during the past year yield a preliminary constraint on the temporal variation of the fine-structure constant alpha of alpha/alpha = (-1.6+/-2.3) x 10(-17)/year.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rosenband, T -- Hume, D B -- Schmidt, P O -- Chou, C W -- Brusch, A -- Lorini, L -- Oskay, W H -- Drullinger, R E -- Fortier, T M -- Stalnaker, J E -- Diddams, S A -- Swann, W C -- Newbury, N R -- Itano, W M -- Wineland, D J -- Bergquist, J C -- New York, N.Y. -- Science. 2008 Mar 28;319(5871):1808-12. doi: 10.1126/science.1154622. Epub 2008 Mar 6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA. trosen@boulder.nist.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18323415" target="_blank"〉PubMed〈/a〉
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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